minor #12109 [VarDumper] Improved dump in html (hason)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[VarDumper] Improved dump in html

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | http://www.w3.org/TR/html5/dom.html#the-id-attribute
| License       | MIT
| Doc PR        | -

Commits
-------

f214eda [VarDumper] Added unique id for every single dump in html

Author: fabpot

Tests/DataCollector/DumpDataCollectorTest.php

@@ -32,18 +32,21 @@ public function testDump()
         $collector->dump($data); $line = __LINE__;
         $this->assertSame(1, $collector->getDumpsCount());
 
+        $dump = $collector->getDumps('html');
+        $this->assertTrue(isset($dump[0]['data']));
+        $dump[0]['data'] = preg_replace('/^.*?<pre/', '<pre', $dump[0]['data']);
+        preg_match('/sf-dump-(\\d{2,})/', $dump[0]['data'], $matches);
+        $dumpId = $matches[1];
+
         $xDump = array(
             array(
-              'data' => "<pre id=sf-dump><span class=sf-dump-0><span class=sf-dump-num>123</span>\n</span></pre><script>Sfjs.dump.instrument()</script>\n",
-              'name' => 'DumpDataCollectorTest.php',
-              'file' => __FILE__,
-              'line' => $line,
-              'fileExcerpt' => false,
+                'data' => "<pre id=sf-dump-{$dumpId}><span class=sf-dump-0><span class=sf-dump-num>123</span>\n</span></pre><script>Sfjs.dump.instrument()</script>\n",
+                'name' => 'DumpDataCollectorTest.php',
+                'file' => __FILE__,
+                'line' => $line,
+                'fileExcerpt' => false,
             ),
         );
-        $dump = $collector->getDumps('html');
-        $this->assertTrue(isset($dump[0]['data']));
-        $dump[0]['data'] = preg_replace('/^.*?<pre/', '<pre', $dump[0]['data']);
         $this->assertSame($xDump, $dump);
 
         $this->assertStringStartsWith(